From ccc861c9ddb2161c026d59a88fe7e36f2c8c6fc3 Mon Sep 17 00:00:00 2001
From: iofall <50991099+iofall@users.noreply.github.com>
Date: Fri, 10 Dec 2021 22:41:42 +0530
Subject: [PATCH 1/3] Remove validation from __init__ for SGDOneClassSVM

Co-authored-by: iofall <50991099+iofall@users.noreply.github.com>
Co-authored-by: arisayosh <15692997+arisayosh@users.noreply.github.com>
---
 sklearn/linear_model/_stochastic_gradient.py | 6 +++---
 sklearn/tests/test_common.py                 | 1 -
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/sklearn/linear_model/_stochastic_gradient.py b/sklearn/linear_model/_stochastic_gradient.py
index c07232b6c23fe..f28936d528956 100644
--- a/sklearn/linear_model/_stochastic_gradient.py
+++ b/sklearn/linear_model/_stochastic_gradient.py
@@ -2098,7 +2098,7 @@ def __init__(
         average=False,
     ):
 
-        alpha = nu / 2
+        alpha = None
         self.nu = nu
         super(SGDOneClassSVM, self).__init__(
             loss="hinge",
@@ -2305,8 +2305,8 @@ def partial_fit(self, X, y=None, sample_weight=None):
             Returns a fitted instance of self.
         """
 
-        alpha = self.nu / 2
         self._validate_params(for_partial_fit=True)
+        alpha = self.nu / 2
 
         return self._partial_fit(
             X,
@@ -2331,7 +2331,6 @@ def _fit(
         offset_init=None,
         sample_weight=None,
     ):
-        self._validate_params()
 
         if self.warm_start and hasattr(self, "coef_"):
             if coef_init is None:
@@ -2404,6 +2403,7 @@ def fit(self, X, y=None, coef_init=None, offset_init=None, sample_weight=None):
             Returns a fitted instance of self.
         """
 
+        self._validate_params()
         alpha = self.nu / 2
         self._fit(
             X,
diff --git a/sklearn/tests/test_common.py b/sklearn/tests/test_common.py
index 8b0796b2b5dbc..f2ea871b3ac64 100644
--- a/sklearn/tests/test_common.py
+++ b/sklearn/tests/test_common.py
@@ -429,7 +429,6 @@ def test_transformers_get_feature_names_out(transformer):
     "GridSearchCV",
     "HalvingGridSearchCV",
     "Pipeline",
-    "SGDOneClassSVM",
     "TheilSenRegressor",
     "TweedieRegressor",
 ]

From b4a782a64d41407e019807e3f7b6bb3087130733 Mon Sep 17 00:00:00 2001
From: iofall <50991099+iofall@users.noreply.github.com>
Date: Sat, 11 Dec 2021 22:47:39 +0530
Subject: [PATCH 2/3] Resolve merge conflicts

Co-authored-by: arisayosh <15692997+arisayosh@users.noreply.github.com>
Co-authored-by: iofall <50991099+iofall@users.noreply.github.com>
---
 sklearn/tests/test_common.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/sklearn/tests/test_common.py b/sklearn/tests/test_common.py
index f2ea871b3ac64..6dbaafbc9e3eb 100644
--- a/sklearn/tests/test_common.py
+++ b/sklearn/tests/test_common.py
@@ -428,7 +428,6 @@ def test_transformers_get_feature_names_out(transformer):
     "FeatureUnion",
     "GridSearchCV",
     "HalvingGridSearchCV",
-    "Pipeline",
     "TheilSenRegressor",
     "TweedieRegressor",
 ]

From 321b7916f0a6fd7408b863919e3b6af89228de2c Mon Sep 17 00:00:00 2001
From: iofall <50991099+iofall@users.noreply.github.com>
Date: Sat, 11 Dec 2021 23:28:13 +0530
Subject: [PATCH 3/3] Add Changelog

Co-authored-by: arisayosh <15692997+arisayosh@users.noreply.github.com>
Co-authored-by: iofall <50991099+iofall@users.noreply.github.com>
---
 doc/whats_new/v1.1.rst | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/doc/whats_new/v1.1.rst b/doc/whats_new/v1.1.rst
index 37dc4c56dc860..453c124cdb741 100644
--- a/doc/whats_new/v1.1.rst
+++ b/doc/whats_new/v1.1.rst
@@ -229,6 +229,11 @@ Changelog
   :pr:`21481` by :user:`Guillaume Lemaitre <glemaitre>` and
   :user:`Andrés Babino <ababino>`.
 
+- |Fix| :class:`linear_model.SGDOneClassSVM` now does not validate in 
+  `__init__`. All the validation is now handled through `fit()` and 
+  `partial_fit()`.
+  :pr:`21944` by :user:`Yogendrasingh <iofall>` and :user: `Arisa Y. <arisayosh>`
+
 :mod:`sklearn.metrics`
 ......................